Step 4: It Works!
The wires can now be connected to the correct battery leads that were pulled out earlier, and when you press the "on" button the calculator will fire right up!
I tested out a few functions and everything calculated correctly.
It's amazing to think you can run low current electrical devices on this penny power hack! It works great, and as long as the cardboard is moist with electrolyte, it should work.
If your battery stops working, try re-soaking the cardboard in a little more vinegar to get it wet, then try again. It should fire right back up!